L-DOPA is a direct precursor to dopamine, and its supplementation can increase dopamine levels in the body. It is known as Levodopa and is one component of most Parkinson’s treatments, and found in high amounts in Mucuna pruriens.
Mucuna Pruriens contains L-DOPA, also known as Levodopa. This is a dopamine precursor and sometimes used as a pharmaceutical to treat Parkinson’s Disease (alongside another compound known as Carbidopa)
Compounds contraindicated with Levodopa/Carbidopa treatment also apply to Mucuna Pruriens and should be approached with caution. This appears to be narrow-eye glaucoma sufferers, those using pharmaceutical MAO inhibitors, and those who have a history of melanoma or suspicious and undiagnosed skin lesions.
L-DOPA crosses the blood-brain barrier whereas dopamine itself cannot. Thus, L-DOPA is used to increase dopamine concentrations in the treatment of Parkinson’s disease and dopamine-responsive dystonia. This treatment was made practical and proven clinically by George Cotzias and his coworkers, for which they won the 1969 Lasker Prize. Once L-DOPA has entered the central nervous system, it is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase, also known as DOPA decarboxylase. Pyridoxal phosphate (vitamin B6) is a required cofactor in this reaction and may occasionally be stacked with L-DOPA, usually in the form of pyridoxine.
Besides the central nervous system, L-DOPA is also converted into dopamine from within the peripheral nervous system. Excessive peripheral dopamine signaling causes many of the adverse side effects seen with sole L-DOPA administration. To bypass these effects, it is standard clinical practice to coadminister (with L-DOPA) a peripheral DOPA decarboxylase inhibitor (DDCI) such as carbidopa (medicines combining L-DOPA and carbidopa are branded as Lodosyn, Sinemet, Parcopa, Atamet, and Stalevo) or with a benserazide (combination medicines are branded Madopar or Prolopa), to prevent the peripheral synthesis of dopamine from L-DOPA. Coadministration of pyridoxine without a DDCI accelerates the peripheral decarboxylation of L-DOPA to such an extent that it negates the effects of L-DOPA administration, a phenomenon that historically caused great confusion.
L-DOPA is produced from the amino acid L-tyrosine by the enzyme tyrosine hydroxylase. It is also the precursor for the monoamine or catecholamine neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). Dopamine is formed by the decarboxylation of L-DOPA.
L-DOPA can be directly metabolized by catechol-O-methyl transferase to 3-O-methyldopa, and then further to vanillactic acid. This metabolic pathway is nonexistent in the healthy body, but becomes important after peripheral L-DOPA administration in patients with Parkinson’s disease or in the rare cases of patients with aromatic L-amino acid decarboxylase enzyme deficiency.
L-Phenylalanine, L-tyrosine, and L-DOPA are all precursors to the biological pigment melanin. The enzyme tyrosinase catalyzes the oxidation of L-DOPA to the reactive intermediate dopaquinone, which reacts further, eventually leading to melanin oligomers.